Two-way damper with adjustable sensitivity



March 28, 1967 c. o. MERCKLE 3,311,302

TWOWAY DAMPER WITH ADJUSTABLE SENSITIVITY Filed March 1, 1965 INVENTORCLAUDE 0. MERCKLE ATTORNEY United States Patent 3,311,302 TWO-WAY DAMPERWITH ADJUSTABLE SENSITIVITY Claude O. iderckle, Hagerstown, Md.,assignor to The Danzer Metal Works Co., Inc., Hagerstown, Md., a

corporation of Maryland Filed Mar. 1, 1965, Ser. No. 436,186 4 Claims.(Cl. 236-45) This invention relates broadly to dampers or draftregulators, and more particularly to a two-way active damper for use invertical flues or pipes.

An important object of the invention is to provide a twoway damper forvertical ducts which may be delicately balanced to a horizontal orclosed postion within the duct and adapted to tilt or open in eitherdirection under the infiuence of barometric pressure changes, drafts,variable weather conditions and the like.

Another important object of the invention is to provide a pivoted damperblade or gate which is held in the normally closed position by variablespring tension, and including novel, compact and simplified means foradjusting the spring tension to thereby regulate the opening and closingof the gate in response to various pressures on either side thereof orin either direction.

Still another object is to provide a two-way damper which is rugged inconstruction and therefore durable, economical to manufacture, andreliable and efficient in operation.

ther objects and advantages of the invention will become apparent duringthe course of the following detailed description.

In the accompanying drawings forming a part of this application and inwhich like numerals are employed to designate like parts throughout thesame,

FIGURE 1 is a perspective view of a two-way damper embodying theinvention, partly broken away;

FIGURE 2 is another perspective view showing the lower side of thedevice, partly broken away; and

FIGURE 3 is a central transverse vertical section taken on line 3-3 ofFIGURE 1.

In the drawings, wherein for the purpose of illustration is shown apreferred embodiment of the invention, the numberal designates acylindrical sleeve constituting the body portion of the damper and whichsleeve may constitute an integral section of an upright pipe, flue orventilating duct or may be a separately formed member for connection inthe pipe, flue or duct.

Rockably mounted Within the bore of the sleeve 10 in relatively closefitting engagement therewith is a damper blade or plate assembly 11consisting of a generally fiat circular damper blade 12 and a supportingrocker shaft 13. As shown in the drawings, the rocker shaft 13 is offsetto one side of the center of the damper blade so that the latter willtilt in either direction upon the offset axis of the rocker shaft inresponse to differences in pressure upon either side thereof. The offsetarrangement of the rocker shaft 13 provides sections of unequal area onthe blade 12 so that it will respond in either direction to pressure.

In order to accommodate the shaft 13, the damper blade 12 is providedwith a generally U-shaped rib or corrugation 14 extending entirelyacross the same generally diametrically although offset from the centerof the blade, as stated. The rocker shaft 13 lies within the confines ofthis rib 14 and is secured rigidly therein by pinning, soldering,welding or by any other suitable means. The uncovered side of the shaft13 is substantially flush with the adjacent fiat side of the damperblade, as shown in FIGURE 3. The blade and rocker shaft thus constitutea permanently assembled substantially rigid unit for operation withinthe sleeve 10.

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End portions 15 of rocker shaft 13 project beyond the opposite sides ofthe damper blade and are held rotatably within suitable bearings 16,anchored within openings in the wall or sleeve 10. The bearings 16 arepreferably Oilite bearings or other conventional low friction bearingsto render the damper blade assembly free tilting with a minimum offriction.

In order to compensate for the natural unbalance of the damper blade onthe axis of the offset rocker shaft, an adjustable counterweight 17 isprovided upon one side of the blade and on the portion thereof which isthe smallest or lightest in weight. A lead weight or the like may beemployed and the weight is slotted as indicated at 18 to facilitateadjusting the weight toward and away from the axis of the rocker shaft13. A screw or bolt 19 may be employed to anchor the weight 17 directlyto the damper blade adjustably, as shown. By this means, the entiredamper blade assembly may be delicately balanced upon the offset axis ofthe shaft 13 so that the assembly will remain in the level or closedposition indicated in FIGURE 3 is there are no unbalancing pressures orforces acting upon the same.

Adjustable resilient means are provided for regulating the opening ofthe damper in either direction in response to pressures thereon and forreturning the damper automatically to its normally closed or draftblocking position shown in the drawings with the desired degree offirmness. This means comprises a relatively small fiat adjustable slideplate 20 on one side of the blade 12 and having an elongated adjustingslot 21 formed therethrough and extending at right angles to the axis ofthe rocker shaft 13. The slide plate 2% is adjustably anchored to thedamper blade by means of a screw 22, whereby the slide plate may beshifted across the shaft 13 in either direction and firmly locked in anyselected adjusted position. A retractile coil spring 23 extendslongitudinally beyond one end of the plate 20 and has one end loopthereof anchored to a small opening 24 in the adjacent end of the slideplate. The remote end of the spring is suitably anchored as at 25 to theside wall of damper sleeve or body portion 10. The spring extendsradially of the damper blade and lies in a common plane substantiallywith the damper blade and the slide plate 20, thus rendering the entireassembly very compact and uncluttered. In order to permit the requiredrelative movement between the spring and the damper blade, the latterhas a radial slot formed therethrough adjacent to the spring andextending from a point near the shaft 13 entirely through the peripheraledge of the damper blade. The slot 26 is adequately wide to permit thepassage of the small spring therethrough without interference wheneverthe damper blade tilts upwardly or downwardly from the normal neutral orlevel position shown in FIGURE 3.

The broken lines and the arrows in FIGURE 3 illustrate diagrammaticallythe ability of the damper to open in either direction by tilting in avertical duct or pipe. The spring 23 yields to allow tilting or openingof the damper in either direction and constantly urges the damper toreturn to the normal closed or neutral position. The sensitivity of thedamper may be regulated through wide limits by simply adjusting thetension of the damper spring by shifting the slide plate longitudinallyof its slot 21 and at right angles to the rocker shaft 13. By thismeans, the damper blade can be rendered quite stiff so that a relativelystrong draft or change in pressure will be required to cause anyappreciable opening or tilting. On the other hand, the damper blade maybe rendered extremely soft-acting or sensitive to slight variations indraft or pressure on either side thereof by adjusting the tension of thespring. Quite obviously. the strength of the spring is increased byshifting the slide plate 20 radially inwardly and the strength of thespring decreased by moving the adjusting slide plate radially outwardly.In any adjusted condition, the force of the spring will serve to holdthe damper blade in the closed or neutral position as depicted in thedrawings. It is believed that the advantages of the construction inproviding a doubleacting damper with simiplicity and ease of adjustmentwill be apparent to anyone skilled in the art,

It is to be understood that the form of the invention herewith shown anddescribed is to be taken as 'a preferred example of the same, and thatvarious changes in the shape, size and arrangement of parts may beresorted to, without departing from the spirit of the invention or scopeof the subjoined claims.

The invention having been described, what is claimed 1. A twow'ay activedamper comprising a damper blade adapted to be mounted in an uprightsleeve section, a rocker shaft pivotally supporting the damper blade inthe bore of the sleeve section for tilting movement on an axis which isoffset from the geometrical center of the damper blade, adjustablecounterbalancing means on the damper blade to permit the damper blade toassume a level bore closing position, said damper blade having a radialslot formed therethrough, an adjusting slide plate on one face of thedamper blade and having an adjusting slot lengthwise of the first-namedslot and at right angles to said axis, means to clamp the slide plate ina selected adjusted position upon the damper blade, and a retractilespring adjacent the first-named slot and adapted to pass through theslot whenever the damper blade tilts in either direction upon said axis,said spring having one end secured to said slide plate and its oppositeend secured to the sleeve section, said spring, damper blade and slideplate all lying substantially, in a common plane when the damper bladeis in the level bore closing position.

2. A two-way damper comprising a damper sleeve, a damper blade tiltablymounted within said sleeve upon a rocker shaft whose axis is offsetlaterally from the center of the damper blade, adjustablecounterbalancing means on the damper blade to allow leveling thereofwithin the sleeve to substantially close the bore of the sleeve, aretractile spring, means to anchor one end of said spring to the sleeve,an adjustable slide plate on the damper blade and secured to the otherend of the spring and operable to regulate the tension of the spring,the spring tending to hold the damper blade in said level position butyielding to permit tilting of the damper blade in opposite directionsfrom said level position, said damper blade having a clearance openingthrough which said spring may pass during said tilting of the damperblade in opposite directions.

3. A two-way draft damper for use in a vertical duct comprising a dampersleeve for connection in said vertical duct, a damper blade within saidsleeve adapted to substantially close the bore of said sleeve when in alevel position, a rocker sh'aft secured to and carrying the damper bladeand being offset from the geometrical center of the damper blade andsleeve, a pair of aligned bearings on the sleeve rota-tably supportingthe ends of the rocker shaft, an adjustable counterbalaneing means onthe damper blade to facilitate leveling the damper blade, an adjustingelement on the damper blade shiftable generally radially thereon "atright angles to the axis of the rocker shaft, a spring connected withsaid element and also connected with said sleeve and being tensioned bytilting of the damper blade in either direction away from said levelposition and thereby tending to return the damper blade to the levelposition, the damper blade having a through passage to permit relativemovement of the damper blade and spring during said tilting.

4. A two-way active damper for a vertical duct comprising a dampersleeve for connection in the duct, a damper blade tiltably mountedwithin the bore of the damper sleeve and adapted to substantially closethe bore when in a level position substantially at right angles to theaxis of the damper sleeve, a retractile spring normally lyingsubstantially in the plane of the damper blade when said blade is level,said spring extending substantially radially of the blade, the damperblade having a radial clearance slot through which the spring may passwithout interfering with the damper blade when the damper blade tilts ineither direction, means anchoring the outer end of the spring to saiddamper sleeve, 'and means forming a radially adjustable connectionbetween the inner end of the spring and damper blade whereby the tensionof the of the spring may be regulated.

References Cited by the Examiner UNITED STATES PATENTS 1,301,455 4/1919Kiessig 137527 2,073,386 3/1937 Cunningham 236-45 2,194,691 3/1940Cornell 236-45 X 2.282,125 5/1942 Firehammer 236-43 WILLIAM J. WYE,Primary Examiner.

ALDEN D. STEWART. Examiner.

1. A TWO-WAY ACTIVE DAMPER COMPRISING A DAMPER BLADE ADAPTED TO BEMOUNTED IN AN UPRIGHT SLEEVE SECTION, A ROCKER SHAFT PIVOTALLYSUPPORTING THE DAMPER BLADE IN THE BORE OF THE SLEEVE SECTION FORTILTING MOVEMENT ON AN AXIS WHICH IS OFFSET FROM THE GEOMETRICAL CENTEROF THE DAMPER BLADE, ADJUSTABLE COUNTERBALANCING MEANS ON THE DAMPERBLADE TO PERMIT THE DAMPER BLADE TO ASSUME A LEVEL BORE CLOSINGPOSITION, SAID DAMPER BLADE HAVING A RADIAL SLOT FORMED THERETHROUGH, ANADJUSTING SLIDE PLATE ON ONE FACE OF THE DAMPER BLADE AND HAVING ANADJUSTING SLOT LENGTHWISE OF THE FIRST-NAMED SLOT AND AT RIGHT ANGLES TOSAID AXIS, MEANS TO CLAMP THE SLIDE PLATE IN A SELECTED ADJUSTEDPOSITION UPON THE DAMPER BLADE, AND A RETRACTILE SPRING ADJACENT THEFIRST-NAMED SLOT AND ADAPTED TO PASS THROUGH THE SLOT WHENEVER THEDAMPER BLADE TILTS IN EITHER DIRECTION UPON SAID AXIS, SAID SPRINGHAVING ONE END SECURED TO SAID SLIDE PLATE AND ITS OPPOSITE END SECUREDTO THE SLEEVE SECTION, SAID SPRING, DAMPER BLADE AND SLIDE PLATE ALLLYING SUBSTANTIALLY, IN A COMMON PLANE WHEN THE DAMPER BLADE IS IN THELEVEL BORE CLOSING POSITION.